Rolling bearings are mounted in power transmission mechanisms of motor vehicles and various kinds of construction machines, such as transmissions, differentials and speed reducers, as well as in travel units in which are mounted these power transmission mechanisms.
In some of these devices, oil used to lubricate the power transmission mechanism is also used to lubricate the rolling bearings.
However, oil stored in the case of a power transmission mechanism, such as a transmission, differential or speed reducer, contains a relatively large amount of foreign objects such as wear dust from gears (which is typically iron dust). If such foreign objects enter one of the rolling bearings, they could become wedged between parts of the bearing, causing peeling of raceways and rolling surfaces, which in turn reduces the durability of the rolling bearing.
In order to prevent entry of foreign objects, it has been proposed to provide a seal ring mounted on the rolling bearing with filters capable of catching foreign objects. Such filters are mounted in oil flow holes formed in the seal ring. (See the below-identified Patent documents 1 and 2.)